Method and apparatus for controlling wireless power of a receiver in a wireless power transmission/reception system

ABSTRACT

A method and apparatus are provided for controlling power in a wireless power transmission/reception system. The method includes receiving power information from a receiver within a charging area; determining whether power is available for the receiver based on the power information; if the power is available for the receiver, transmitting, to the receiver, a first response requesting the receiver to perform charging; and if the power is not available for the receiver, transmitting, to the receiver, a second response requesting the receiver to maintain a standby state

PRIORITY

This application is a Continuation of U.S. Ser. No. 14/704,467, whichwas filed in the U.S. Patent and Trademark Office (USPTO) on May 5,2015, which is a Continuation of U.S. Ser. No. 13/490,963, which wasfiled in the USPTO on Jun. 7, 2012, issued as U.S. Pat. No. 9,024,484 onMay 5, 2015, and claims priority under 35 U.S.C. § 119 to U.S.Provisional Patent Application Ser. No. 61/494,175, which was filed inthe USPTO on Jun. 7, 2011, and Korean Patent Application Serial No.10-2012-0060595, which was filed in the Korean Intellectual PropertyOffice on Jun. 5, 2012, the entire disclosure of each of which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to a wireless power transmissionand reception system, and more particularly, to a method and apparatusfor controlling power of a receiver in a wireless power transmission andreception system, wherein a wireless power quantity supplied toreceivers from a transmitter is controlled through communication betweenthe receivers.

2. Description of the Related Art

Wireless charging (or non-contact) technology uses wireless powertransmission and reception, for example, to charge a battery of anelectronic device by placing the electronic device on a charging pad,without having to connect a separate charging connector to theelectronic device.

Wireless charging technology may be roughly divided into anelectromagnetic induction type using a coil, a resonance type usingresonance, and a Radio Frequency (RF)/micro wave radiation type fortransforming electrical energy into a microwave.

In the resonance type of the wireless charging technology, a resonancetype power transmission principle is used to wirelessly transmitelectricity a distance of several meters from a charging device.Basically, resonance type power transmission uses a similar concept ofphysics in which vibration of a tuning fork causes a wine glass besidethe tuning fork to vibrate at the same frequency. However, instead ofresonating sound, resonance type power transmission resonates anelectromagnetic wave containing electrical energy.

The resonated electrical energy is directly delivered to a device havinga same resonance frequency, and the non-used portion of the resonatedelectrical energy is absorbed again into an electromagnetic field,instead of being spread through the air, such that unlike otherelectromagnetic waves, the resonated electrical energy does not to havean influence upon a peripheral machine or human body.

When charging using the resonance type of the wireless chargingtechnology, each of a plurality of receivers that wants chargingrequests transmission of wireless power from a transmitter fortransmitting the wireless power. The transmitter then supplies wirelesspower to each of the receivers. Basically, the receiver requests thetransmitter to transmit wireless power, and is supplied with wirelesspower from the transmitter in response to the request.

Additionally, a single transmitter may charge a plurality of receiversat the same time. Further, when a receiver is being charged, i.e.,supplied with wireless power from the transmitter, the transmitter mayreceive a request to transmit wireless power from another receiver.

However, when a plurality of receivers are supplied with wireless powerfrom a transmitter at the same time, an over-powered state ofover-voltage or over-current may occur in the transmitter or thereceivers. Thereafter, the transmitter or receivers stop the charging,for example, by short-circuiting a circuit or the like, to protectagainst over powering. However, when the transmitter or the receiversstop the charging in this way, inconveniently, a user cannot charge thereceiver using the transmitter or cannot use the receiver.

SUMMARY OF THE INVENTION

Accordingly, the present invention is designed to address at least theproblems and/or disadvantages described above and to provide at leastthe advantages described below.

An aspect of the present invention is to provide a method and apparatusfor controlling power of a receiver in a wireless power transmission andreception system, wherein a wireless power quantity supplied toreceivers from a transmitter is controlled through communication betweenthe receivers.

According to an aspect of the present invention, a method is providedfor controlling wireless power at an electronic device. The methodincludes receiving power information from a receiver within a chargingarea; determining whether power is available for the receiver based onthe power information; if the power is available for the receiver,transmitting, to the receiver, a first response requesting the receiverto perform charging; and if the power is not available for the receiver,transmitting, to the receiver, a second response requesting the receiverto maintain a standby state.

According to another aspect of the present invention, an electronicdevice is provided for controlling wireless power. The electronic deviceincludes a communication unit; and a processor configured to receive,through the communication unit, power information from a receiver withina charging area, determine whether power is available for the receiverbased on the power information, control the communication unit totransmit, to the receiver, a first response requesting the receiver toperform charging, if the power is available for the receiver, andcontrol the communication unit to transmit, to the receiver, a secondresponse requesting the receiver to maintain a standby state, if thepower is not available for the receiver.

According to another aspect of the present invention, a method isprovided for receiving wireless power at a receiver. The method includestransmitting power information to an electronic device; performingcharging, if a first response is received indicating that the wirelesspower is available from the electronic device; and maintaining a standbystate, if a second response is received indicating that the wirelesspower is not available from the electronic device.

According to another aspect of the present invention, a receiver isprovided for receiving wireless power. The receiver includes acommunication unit; and a controller configured to control thecommunication unit to transmit power information to an electronicdevice, perform charging, if a first response is received through thecommunication unit indicating that the wireless power is available fromthe electronic device, and maintain a standby state, if a secondresponse is received through the communication unit indicating that thewireless power is not available from the electronic device.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present invention will be more apparent from thefollowing detailed description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a block diagram illustrating a wireless power transmission andreception system according to an embodiment of the present invention;

FIG. 2 is a block diagram illustrating a transmitter and a receiver in awireless power transmission and reception system according to anembodiment of the present invention;

FIG. 3 is a signal flow diagram illustrating a method for controllingpower of receivers in a wireless power transmission and reception systemaccording to an embodiment of the present invention;

FIG. 4 is a flowchart illustrating a method for controlling power of areceiver in a wireless power transmission and reception system accordingto an embodiment of the present invention;

FIG. 5 is a flowchart illustrating a method for controlling power of areceiver in a wireless power transmission and reception system accordingto an embodiment of the present invention;

FIGS. 6A and 6B are graphs showing a wireless power quantity transmittedto a receiver in a wireless power transmission and reception systemaccording to prior art;

FIGS. 7A and 7B are graphs showing a wireless power quantity transmittedto a receiver in a wireless power transmission and reception systemaccording to an embodiment of the present invention; and

FIGS. 8A and 8B are graphs showing a wireless power quantity transmittedto a receiver in a wireless power transmission and reception systemaccording to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Various embodiments of the present invention will be described in detailbelow with reference to the accompanying drawings. In the followingdescription, specific items such as detailed components are described,and it is apparent to those of ordinary skill in the art that thosespecific items are provided only for overall understanding of thepresent invention and predetermined changes or modifications can be madewithout departing from the scope of the present invention.

FIG. 1 is a block diagram illustrating a wireless power transmission andreception system according to an embodiment of the present invention.

Referring to FIG. 1, a wireless power transmission and reception systemincludes a transmitter 100 and N receivers 200, i.e., a first receiver200-1 and a second receiver 200-2 through an Nth receivers 200-N.

The transmitter 100 transmits wireless power to the receivers 200. Thetransmitter 100 includes a resonator (hereinafter, a ‘Tx resonator’),and transmits wireless power to the receivers 200 by resonating carrierfrequencies including electrical energy using the Tx resonator.

The receivers 200 transmit control signals, via communicationinterfaces, requesting the transmitter 100 to supply wireless power, andreceive the wireless power from the transmitter 100. The receivers 200include resonators (hereinafter, ‘Rx resonators’) for receiving thewireless power from the transmitter 100.

Additionally, the resonators also generate a signal in a particularfrequency band, such that the receivers 200 may request supply of thewireless power from the transmitter 100 by resonating carrierfrequencies in a frequency band for supply of the wireless power throughthe Rx resonators. The transmitter 100 also receives wireless powertransmission requests from the receivers 200 through the Tx resonator.

In accordance with an embodiment of the present invention, each of thereceivers 200 communicates with each other, when in a range in which thetransmitter 100 can transmit wireless power. Herein, an area in whichthe transmitter 100 can transmit wireless power will be referred to as a“charging area.” For example, assuming that the first receiver 200-1 andthe second receiver 200-2 are located in the charging area, the firstreceiver 200-1 and the second receiver 200-2 communicate with each otherusing their respective wired or wireless communication interfaces.

When a new receiver 200 joins the charging area, the new receiver 200requests the transmitter 100 to transmit required power thereto. Herein,receivers previously included in the charging area will be referred toas “registered receivers” and a receiver newly joining the charging areawill be referred to as a “joining receiver.” The registered receiversreceive a power transmission request transmitted from the joiningreceiver to the transmitter 100 and analyze the desired-powertransmission request in order to calculate the required power with whichthe joining receiver desires to be supplied from the transmitter 100.The registered receivers then determine if the transmitter 100 cansupply the required power of the joining receiver.

For example, when the transmitter 100 can supply wireless power of 50Win total to the receivers 200 and the transmitter 100 is alreadysupplying 45W of wireless power to the registered receivers included inthe charging area, when the joining receiver requests 7W of wirelesspower from the transmitter 100, the transmitter 100 cannot supply thepower to the joining receiver because the remaining power of thetransmitter 100 is only 5W. In accordance with an embodiment of thepresent invention, the transmitter 100 supplies only wireless power atthe request of the receivers 200, such that the registered receivers, inplace of the transmitter 100, may inform the joining receiver that therequired power of 7W cannot be supplied by the transmitter 100.

In accordance with another embodiment of the present invention, thejoining receiver may calculate the remaining power of the transmitter100. The joining receiver receives control signals from the registeredreceivers in the charging area, for example, charging power information,and determines whether the transmitter 100 can transmit the requiredpower to the joining receiver based on the charging power information.

In accordance with an embodiment of the present invention, the chargingpower information broadcast from the registered receivers includes awireless power quantity supplied to the respective registered receivers,and a total wireless power quantity that the transmitter 100 can supply.Therefore, based on the charging power information, the joining receivercalculates the remaining power of the transmitter 100 and determineswhether the calculated remaining power is larger than the power desiredby the joining receiver. If the remaining power of the transmitter 100is smaller than the power desired by the joining receiver, thetransmitter 100 cannot supply the desired power to the joining receiver.Therefore, the joining receiver requests the transmitter 100 to transmitthe desired power only when the remaining power of the transmitter 100is larger than the desired power of the joining receiver.

In accordance with another embodiment of the present invention, thereceivers 200 included in the charging area broadcast the charging powerinformation at preset broadcasting intervals. For example, when thefirst receiver 200-1 is being supplied with 5W of wireless power fromthe transmitter 100, the first receiver 200-1, the second receiver200-2, and a third receiver 200-3 are included in the charging area, anda broadcasting interval of the first receiver 200-1 is 5 minutes, thefirst receiver 200-1 broadcasts a signal to the charging area indicatingthat it is supplied with 5W of wireless power from the transmitter 100every 5 minutes,.

FIG. 2 is a block diagram illustrating structures of a transmitter and areceiver in the wireless power transmission and reception systemaccording to an embodiment of the present invention.

Referring to FIG. 2, the transmitter 100 includes a Tx resonator 102, aTx matching inductance (L)/capacitance (C) circuit), a Tx powerconverter 106, and a Tx Micro Control Unit (MCU) 110. The Tx resonator102 is coupled with an Rx resonator 202 of the receiver 200 to resonatean Alternating Current (AC) voltage into a resonance wave, therebysupplying wireless power to the receiver 200. Additionally, the Txresonator 102 receives various control signals, e.g., the charging powerinformation, the requested power information, etc., transmitted from thereceiver 200.

The Tx matching L/C 104 includes an impedance that is matched for the Txresonator 102 and the Rx resonator 202 to be coupled and the Rxresonator 202 to smoothly receive the resonance wave resonated from theTx resonator 102. The Tx matching L/C 104 controls the impedance undercontrol of the Tx MCU 110.

The Tx power converter 106 converts a Direct Current (DC) voltage inputfrom a DC adaptor (not shown) connected with the transmitter 100 into anAC voltage. For voltage conversion, the Tx power converter 106 includes,for example, a Class-E amplifier (not shown) and a driver amplifier (notshown). The Driver Amp converts a DC voltage input from the DC adaptorinto an AC voltage. The Class-E Amp amplifies the AC voltage amplifiedby the Driver Amp under control of the Tx MCU 110.

The transmitter 100 receives, for example, a DC voltage of 7-15V from aDC adaptor (not shown). Upon input of the DC voltage, the Tx MCU 110controls the Tx power converter 106 to convert the DC voltage into an ACvoltage and to amplify the converted AC voltage. The Tx MCU 110regulates an amplification rate of the AC voltage in the Tx powerconverter 106. The amplified AC voltage is delivered to the Rx resonator202 of the receiver 200 by the Tx resonator 102.

The Tx MCU 110 controls overall operation of the transmitter 100.Specifically, the Tx MCU 110 controls the transmitter 100 to receive theDC voltage from the DC adaptor, and controls the Tx power converter 106to regulate the power of the amplified AC voltage. Once the charging ofthe receiver 200 is completed, the transmitter 100 may be controlled notto transmit power to the receiver 200 anymore. The Tx MCU 110 regulatesthe impedance of the Tx matching L/C 104 to facilitate powertransmission of the transmitter 100. The Tx MCU 110 compares the powertransmitted from the transmitter 100 with the power delivered to thereceiver 200 to calculate a power efficiency. Based on the calculatedpower efficiency, the Tx MCU 110 regulates the impedance of the Txmatching L/C 104 in order to maximize the power efficiency.

The receiver 200 includes the Rx resonator 202, an Rx matching L/C 204,an Rx power converter 206, a communication interface 208, and an Rx MCU210. The Rx resonator 202 is coupled with the Tx resonator 102 toreceive a resonated resonance wave from the Tx resonator 102, thus beingsupplied with wireless power from the transmitter 100.

The Rx matching L/C 204 regulates an impedance to be matched for the Txresonator 102 and the Rx resonator 202 to be coupled and a resonatedresonance wave to be smoothly received from the Tx resonator 102. Atotal impedance of the Tx matching L/C 104 and a total impedance of theRx matching L/C 204 are preferably matched to have the same value.

The Rx power converter 206 converts the AC voltage received through theRx resonator 202 into the DC voltage. For voltage conversion, the Rxpower converter 206 includes, for example, an AC/DC rectifier (notshown) and a DC/DC converter (not shown). The AC/DC rectifier convertsthe AC voltage received through the Rx resonator 202 into the DCvoltage, and the DC/DC converter amplifies the DC voltage convertedthrough the AC/DC rectifier. The Rx power converter 206 delivers the DCvoltage output through the DC/DC converter to a device connected withthe receiver 200, e.g., a portable terminal, such that the portableterminal can be driven by the DC voltage.

The communication interface 208 performs wired or wireless communicationof the receiver 200. The communication interface 208 transmits a controlsignal requesting power supply or stopping of the power supply from thetransmitter 100 to the transmitter 100. The communication interface 208broadcasts the control signal to the charging area.

The communication interface 208 also communicates with another receiverin the charging area, and receives a control signal broadcast from theanother receiver. For example, the control signal includes a wirelesspower request signal for requesting wireless power from the transmitter100, a status signal indicating the current status of the receiver 200,etc.

The Rx MCU 210 controls the overall operation of the receiver 200. TheRx MCU 210 controls the receiver 200 to deliver a DC voltage for drivinga portable terminal connected with the receiver 200.

The Rx MCU 210 controls the Rx power converter 206 to regulate anamplification rate of an amplified DC voltage. The Rx MCU 210 alsoregulates the impedance of the Rx matching L/C 204 to smoothly receivewireless power delivered through the Tx resonator 102 of the transmitter100.

The Rx MCU 210 generates a control signal broadcast through thecommunication interface 208 to the transmitter 100 and registeredreceivers included in the charging area or a joining receiver. The RxMCU 210 controls the communication interface 208 to receive controlsignals broadcast from the registered receives included in the chargingarea or the joining receiver. The Rx MCU 210 identifies a wireless powerquantity (charging power) supplied to the respective registered receivesincluded in the charging area or a wireless power quantity (requiredpower) requested by the joining receiver from the control signals. TheRx MCU 210 calculates a total wireless power quantity of the wirelesspower supplied to the respective registered receivers, and calculates aremaining power quantity of the transmitter 100 using the total wirelesspower quantity. The Rx MCU 210 also determines whether the remainingpower quantity is larger than the required power quantity of the joiningreceiver. If the remaining power quantity is smaller than the requiredpower quantity of the joining receiver, then the Rx MCU 210 controls thecommunication interface 208 to generate a standby request control signaland to transmit the generated standby request control signal to thejoining receiver.

If the receiver 200 is a joining receiver, the Rx MCU 210 determineswhether the remaining power quantity is larger than a desired powerquantity. If the remaining power quantity is smaller than the desiredpower quantity, the joining receiver maintains a standby state withoutrequesting the transmitter 100 to supply the desired power. The Rx MCU210 generates a control signal indicating maintenance of the standbystate and broadcasts the control signal to the transmitter 100 and theregistered receivers included in the charging area through thecommunication interface 208.

FIG. 3 is a signal flow diagram illustrating a method for controllingpower of receivers in a wireless power transmission and reception systemaccording to an embodiment of the present invention.

Referring to FIG. 3, in step S302, i.e., a charging state, the firstreceiver 200-1 receives wireless power from the transmitter 100.

In step S304, the second receiver 200-2, which is a joining receiver,enters the charging area.

In step S306, the second receiver 200-2 requests joining from thetransmitter 100. Specifically, the Rx MCU 210 of the second receiver200-2 generates a joining request control signal for requesting joiningfrom the transmitter 100, and transmits the joining request controlsignal to the transmitter 100 through the communication interface 208.

In step S306, the second receiver 200-2 transmits a control signalincluding required power information to the transmitter 100.Specifically, the second receiver 200-1 transmits the required powerinformation to the transmitter 100 by broadcasting the control signalincluding the required power information to the charging area. Therequired power information indicates a wireless power quantity thejoining receiver, i.e., the second receiver 200-2, requires from thetransmitter 100. The first receiver 200-1 receives the control signalbroadcast by the second receiver 200-2. As described above, the firstreceiver 200-1 receives the control signals transmitted to thetransmitter 100 in order to acquire the required power information ofthe second receiver 200-2.

In step S308, the first receiver 200-1 calculates a remaining power ofthe transmitter 100. The first receiver 200-1, together with respectiveregistered receivers included in the charging area, knows a totalwireless power quantity that is being supplied or is to be supplied fromthe transmitter 100. The first receiver 200-1 also knows the totalwireless power quantity that can be output from the transmitter 100.Using this information, the first receiver 200-1 calculates theremaining power of the transmitter 100.

In step S310, the first receiver 200-1 determines whether thetransmitter 100 can supply the required power to the second receiver200-2, based on the remaining power of the transmitter 100.

If the transmitter 100 can supply the required power to the secondreceiver 200-2 (YES in step S310), the first receiver 200-1 does notperform any subsequent operation. However, if the transmitter 100 cannotsupply the required power to the second receiver 200-2 (NO in stepS310), the first receiver 200-1 requests the second receiver 200-2 tomaintain a standby state in step S312. Specifically, the Rx MCU 210 ofthe first receiver 200-1 generates a standby state request signal andtransmits the standby state request signal to the second receiver 200-2through the communication interface 208.

In step S314, the second receiver 200-2 maintains the standby state.

In accordance with an embodiment of the present invention, the firstreceiver 200-1 determines in step S310 that the transmitter 100 cannotsupply the required power to the second receiver 200-2 if the remainingpower of the transmitter 100, after transmitting the required power thesecond receiver 200-2 would be smaller than a preset reference value,although the total remaining power, prior to transmitting the requiredpower the second receiver 200-2, is larger than the power the secondreceiver 200-2 requires from the transmitter 100. For example, when therequired power of the second receiver 200-2 is 7W, the remaining powerof the transmitter 100 is 9W, and the reference value is 3W, the firstreceiver 200-1 determines that the remaining power of the transmitter100, i.e., 2W, would be smaller than the reference value, i.e., 3W, whenthe transmitter 100 supplies wireless power to the second receiver200-2. Therefore, in this case, the first receiver 200-1 determines thatthe transmitter 100 cannot supply the required power to the secondreceiver 200-2.

As described above, a registered receiver instructs a joining receiverto maintain a standby state in order to prevent a circuit included inthe transmitter 100 or the receiver 200 from being damaged by overloading even when the remaining power of the transmitter 100 is largerthan the required power of the joining receiver.

FIG. 4 is a flowchart illustrating a method for controlling power of ajoining receiver by a registered receiver in a wireless powertransmission and reception system according to an embodiment of thepresent invention.

Referring to FIG. 4, in step S322, the receiver 200, i.e., theregistered receiver, receives required power information broadcast fromthe joining receiver through the communication interface 208. Forexample, the receiver 200 receives a control signal including therequired power information.

In step S324, the receiver 200 calculates the remaining power of thetransmitter 100. In step S326, the receiver 200 determines whether therequired power of the joining receiver is larger than the remainingpower of the transmitter 100.

If the required power of the joining receiver is larger than theremaining power of the transmitter 100 (YES in step S326), the receiver200 requests the joining receiver to maintain the standby state in stepS328. Specifically, the Rx MCU 210 of the receiver 200 generates astandby state request signal and transmits the standby state requestsignal to the joining receiver through the communication interface 208.

In step S330, the receiver 200 checks, e.g., at predetermined intervals,if its charging has been completed. When the charging has been completed(YES in step S330), the receiver 200 requests the joining receiver toperform charging in step S332. The receiver 200 that has been completelycharged maintains the standby state or leaves the charging area.

If the required power of the joining receiver is smaller than theremaining power of the transmitter 100 (NO in step S326), the receiver200 requests the joining receiver to perform charging in step S332.Alternatively, if the required power of the joining receiver is smallerthan the remaining power of the transmitter 100 (NO in step S326), thereceiver 200 may take no further action.

FIG. 5 is a flowchart illustrating a method for controlling power of ajoining receiver, by the joining receiver, in a wireless powertransmission and reception system according to an embodiment of thepresent invention.

Referring to FIG. 5, the receiver 200, i.e., the joining receiver,enters the charging area in step S342.

In step S344, the receiver 200 transmits required power information tothe transmitter 100 through the communication interface 208.Specifically, the receiver 200 generates a control signal including therequired power information and transmits the control signal to thetransmitter 100.

In step S346, the receiver 200 receives charging power information fromrespective registered receives included in the charging area through thecommunication interface 208. Alternatively, steps S344 and S346 may beperformed at the same time, or the order of these steps may beinterchanged.

As described above, the charging power information includes a wirelesspower quantity with which the registered receiver is being supplied fromthe transmitter 100, and further includes a total wireless powerquantity the transmitter 100 can supply to the receiver 200.

The receiver 200 calculates the remaining power of the transmitter 100based on the charging power information and determines whether theremaining power of the transmitter 100 is larger than a required powerin step S348.

If the remaining power of the transmitter 100 is larger than therequired power (YES in step S348), the receiver 200 requests thetransmitter 100 to supply the required power in step S350. In step S352,the receiver 200 performs a charging operation by receiving the wirelesspower from the transmitter 100.

However, if the remaining power of the transmitter 100 is smaller thanthe required power in step S348, the receiver 200 maintains the standbystate in step S354.

FIGS. 6A and 6B are graphs showing a wireless power quantity transmittedto a receiver in a wireless power transmission and reception systemaccording to prior art. Specifically, FIG. 6A shows a total load (TotalRXs Load (W)) applied to receivers (RXs), and FIG. 6B shows a wirelesspower quantity, i.e., an input voltage (RX1 Input Voltage (V)) withwhich the first receiver RX1 200-1 among the registered receivers issupplied from the transmitter 100.

Referring to FIGS. 6A and 6B, when the first receiver RX1 200-1 issupplied with the input voltage from the transmitter 100 and the secondreceiver RX2 200-2 enters the charging area at time t₁₁ to be suppliedwith wireless power from the transmitter 100, a load (RX2 load) isapplied. As the second receiver RX2 enters the charging area, a load inthe charging area changes. Because the wireless power is supplied to thesecond receiver RX2, a total load (Total RXs Load) applied to thereceivers 200 sharply increases from the time t₁₁, and exceeds a totalpower capacity (TX Power Capacity), which can be supplied from thetransmitter 100 to the receivers 200.

Further, the input voltage of the first receiver RX1 sharply decreases,such that the input voltage supplied to the first receiver RX1 may dropbelow a threshold voltage. In FIG. 6B, the input voltage supplied to thefirst receiver RX1 sharply drops below the threshold voltage from thetime t₁₁. The first receiver RX1 is reset at time t₁₂ (RX1 reset) torequest the transmitter 100 to transmit the input voltage, a load changeby the first receiver RX1 occurs at t₁₃, and the first receiver RX1 issupplied with the input voltage larger than the threshold voltage fromthe transmitter 100. However, due to the second receiver RX2 200-2, atotal wireless power quantity supplied to the receivers 200 sharplyincreases from the time t₁₃ at which the first receiver RX1 is suppliedwith the input voltage, such that the total wireless power quantityexceeds the total power capacity of the transmitter 100. Thus, the firstreceiver RX1 is turned off again and reset again at time t₁₄ (RX1 resetagain).

FIGS. 7A and 7B are graphs showing a wireless power quantity transmittedto a receiver in the wireless power transmission and reception systemaccording to an embodiment of the present invention. Specifically, FIG.7A is a graph showing a total load (Total RXs Load (W)) applied to thereceivers 200 RXs, and FIG. 7B is a graph showing a wireless powerquantity, that is, an input voltage (RX1 Input Voltage (V)) with whichthe first receiver RX1 200-1 among the registered receivers is suppliedfrom the transmitter 100.

Referring to FIGS. 7A and 7B, when the first receiver RX1 200-1 issupplied with the input voltage from the transmitter 100 and the secondreceiver RX2 200-2 enters the charging area at time t₂₁ to be suppliedwith the wireless power from the transmitter 100 (RX2 load), thetransmitter 100 senses a load change generated in the charging area, andreceives required power information transmitted from the second receiverRX2. The first receiver RX1 is temporarily turned off based on therequired power information to reduce the input voltage supplied from thetransmitter 100 to the threshold voltage. If the input voltage suppliedto the first receiver RX1 during t₂₂ is reduced to the threshold voltageor less, the total load amount (Total RXs Load) supplied to thereceivers 200 does not exceed the total power capacity (Tx PowerCapacity) of the transmitter 100.

FIGS. 8A and 8B are graphs showing a wireless power quantity transmittedto a receiver in a wireless power transmission and reception systemaccording to an embodiment of the present invention. Specifically, FIG.8A is a graph showing a total load (Total RXs Load (W)) applied to thereceivers RXs, and FIG. 8B is a graph showing an estimated wirelesspower quantity (Estimated TX Power Budget (W)) supplied to the receivers200 by the transmitter TX 100.

Referring to FIGS. 8A and 8B, at time t₃₁, a load is applied to a clientdevice including the receivers 200. Thus at time t₃₂, the receiver RXmay be turned on to transmit required power information of the clientdevice to the transmitter 100. In FIGS. 8A and 8B, it is assumed that athreshold value for a total wireless power quantity that can be suppliedto the receivers 200 by the transmitter 100 is W1 and a required powerquantity of the client device is W2.

The transmitter 100 estimates a total wireless power quantity based onthe required power information of the client device.

Referring to FIGS. 8A and 8B, when a load is applied to both the clientdevice and the receivers 200, then an estimated wireless power quantitysupplied to the client device and the receivers 200 exceeds thethreshold value W1. Thus, the receiver RX maintains the standby state attime t₃₃ and only the client device may be supplied with wireless powerfrom the transmitter 100.

While the present invention has been particularly shown and describedwith reference to certain embodiments thereof, it will be understood bythose of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims and theirequivalents.

What is claimed is:
 1. A method for controlling wireless power at an electronic device, the method comprising: receiving power information from a receiver within a charging area; determining whether power is available for the receiver based on the power information; if the power is available for the receiver, transmitting, to the receiver, a first response requesting the receiver to perform charging; and if the power is not available for the receiver, transmitting, to the receiver, a second response requesting the receiver to maintain a standby state.
 2. The method of claim 1, wherein the first response includes information about an amount of available power of the electronic device.
 3. The method of claim 1, wherein the first response includes a total power quantity capable of being supplied to the receiver from the electronic device.
 4. The method of claim 1, wherein determining whether the power is available for the receiver comprises: identifying remaining power of the electronic device; and determining whether the remaining power is larger than available power for charging the receiver.
 5. The method of claim 4, further comprising, if the remaining power is not larger than the available power for charging the receiver, determining that the power is not available for the receiver.
 6. The method of claim 1, further comprising, if the power is not available for the receiver, transmitting a request to wait for another response from the electronic device.
 7. The method of claim 6, further comprising: identifying a total amount of power capable of being supplied to the receiver from the electronic device; and determining whether the total amount of power is larger than available power for charging the receiver.
 8. The method of claim 7, further comprising, if the total amount of power is larger than the available power for charging the receiver, determining that the power is available for the receiver.
 9. An electronic device for controlling wireless power, the electronic device comprising: a communication unit; and a processor configured to: receive, through the communication unit, power information from a receiver within a charging area, determine whether power is available for the receiver based on the power information, control the communication unit to transmit, to the receiver, a first response requesting the receiver to perform charging, if the power is available for the receiver, and control the communication unit to transmit, to the receiver, a second response requesting the receiver to maintain a standby state, if the power is not available for the receiver.
 10. The electronic device of claim 9, wherein the first response includes an amount of available power of the electronic device.
 11. The electronic device of claim 9, wherein the first response includes a total amount of power capable of being supplied to the receiver from the electronic device.
 12. The electronic device of claim 9, wherein the processor is further configured to: identify remaining power of the electronic device, and determine whether the remaining power is larger than available power for charging the receiver.
 13. The electronic device of claim 12, wherein the processor is further configured to, if the remaining power is not larger than the available power for charging the receiver, determine that the power is not available for the receiver.
 14. The electronic device of claim 9, wherein the processor is further configured to control the communication unit to transmit a request to wait for another response from the electronic device, if the power is not available for the receiver.
 15. The electronic device of claim 16, wherein the processor is further configured to: identify a total amount of power capable of being supplied to the receiver from the electronic device, and determine whether the total amount of power is larger than available power for charging the receiver.
 16. The electronic device of claim 15, wherein the processor is further configured to, if the total amount of power is larger than the available power for charging the receiver, determine that the power is available for charging the receiver.
 17. A method for receiving wireless power at a receiver, the method comprising: transmitting power information to an electronic device; performing charging, if a first response is received indicating that the wireless power is available from the electronic device; and maintaining a standby state, if a second response is received indicating that the wireless power is not available from the electronic device.
 18. The method of claim 17, wherein the first response includes information about an amount of the available power of the electronic device.
 19. The method of claim 17, wherein the first response includes a total amount of power capable of being supplied to the receiver from the electronic device.
 20. The method of claim 17, further comprising, if the wireless power is not available from the electronic device, waiting for another response from electronic device.
 21. A receiver for receiving wireless power, the receiver comprising: a communication unit; and a controller configured to: control the communication unit to transmit power information to an electronic device, perform charging, if a first response is received through the communication unit indicating that the wireless power is available from the electronic device, and maintain a standby state, if a second response is received through the communication unit indicating that the wireless power is not available from the electronic device.
 22. The receiver of claim 21, wherein the first response includes an amount of the available power of the electronic device.
 23. The receiver of claim 21, wherein the first response includes a total amount of power capable of being supplied to the receiver from the electronic device.
 24. The receiver of claim 21, wherein the controller is further configured to wait for another response from the electronic device, if the wireless power is not available from the electronic device. 